To build a basic yeast cell, you would have to miniaturize the same number of components tha tmake up a jet 777 and squeeze them into a space 5 microns across
Human cells are way more complicated
A cell contains millions of objects working to extract energy, getting rid of waste, protecting itself,making repairs.
A cell will contain some 20,000 different types of proteins.
A typical cell will have about one billion ATP molecules, which are energy. Every 2 minutes they will be used up and require another billion to replace them.
"Even the simplest [cells] are far beyond the limits of human ingeniuty"
"In ways that we have barely begun to understand, trillions upon trillions of reflexive chemical reactions add up to a mobile, thinking, decision-making you - or come that that, a rather less reflective, but still incredibly organized dung beetle. Ever living thing, never forget, is a wonder of atomic engineering."